1. Field of the Invention
The present invention relates to a projection-type image display device and a projection-type image display system, each of which include a projection optics projecting image light onto a screen.
2. Description of the Related Art
Conventionally, there has been known a projection-type image display device having an optical modulator configured to modulate light emitted from a light source and a projection lens configured to project light, which is outputted from the optical modulator onto a screen.
To display a larger image on a screen, it is needed to take a longer distance between the projection lens and the screen. Regarding this background, there has been proposed a projection-type image display system configured to shorten the distance between a projection-type image display device and a screen by utilizing a reflection mirror reflecting light, which is outputted from the projection lens, toward the screen (see, for example, Japanese Patent Publication No. 2004-45894 (claim 1, FIG. 2, and the like)).
When the distance between the projection-type image display device and the screen is shortened, the projection-type image display device comes close to the screen and thus comes into sight of users. For this reason, an oblique projection is needed from an upper, lower, or lateral side of the screen. For example, in the above-mentioned projection-type image display system, positions of the optical modulator and the projection optics are shifted in vertical directions and a convex mirror is used as a reflection mirror, so that a projection distance is shortened and the oblique projection is performed with a shortened projection distance.
In addition, to shorten the distance between the projection-type image display device and the screen, the reflection mirror is disposed in such a position at such an angle that light outputted from the projection lens can obliquely enter the screen. For example, in the above-mentioned projection-type image display system, a convex lens is used as the reflection mirror to shorten the distance between the projection-type image display device and the screen.
To properly display an image on a screen, the positioning of the reflection mirror is an element of substantial importance. Accordingly, when a user touches the reflection mirror, an angle or the like of the reflection mirror is changed, which obstructs proper display of an image to be projected on the screen.